Today, the majority of truck and tractor chassis are built around two beams that run the entire length of the vehicle. These beams are traditionally called frame rails. The frame rails are connected to each other by secondary beam structures commonly referred to as cross-members. The primary purpose of these cross-members is to form a rigid structure with the frame rail where forces and loads can be transferred from one frame rail to another so that the frame components work together as a system. A secondary function of the cross-members is to provide a surface for mounting other vehicle components such as pneumatic and electrical lines, pneumatic valves, air tanks, drive shaft supports, axle suspension equipment, engine components and towing devices.
The frame rail and cross-member system is widely used in vehicle manufacturing. As such, there are many different design shapes, materials and concepts used for cross-member construction. Typically, cross-members have a center section that is in the shape of a C-channel and tie plates, which are bolted, riveted and/or welded to ends of the C-channel. Cross-members must provide support for a frame rail that is under stress due to different loads placed on the frame. Typical frame rail stresses include: frame roll, frame twist or shear and frame parallelogramming. Frame roll is defined as stress on the frame where the frame “rolls” to the side about the center of the frame's axis. Frame roll usually results from the load put on the frame by fuel tanks, battery boxes and other components attached to the frame rail. Frame twist or shear occurs where one frame rail is displaced vertically in relation to the other frame rail. Frame parallelogramming occurs when one frame rail is displaced fore and aft in relation to the other frame rail.
FIG. 1 depicts an over-the-highway tractor frame consistent with the prior art. The tractor frame 1 consist of frame rails 2 and 3, a plurality of cross-members 4, an over the transmission cross-member 5 and a rear closing cross-member 6. Such a design includes cross-members that are bulky and heavy. By making the cross-member system with several sections that are heavy, the total weight of the vehicle is increased.
Many cross-member designs do not allow for convenient serviceability. A repair shop making repairs to a cross member system currently needs to cut the old cross-member in half with a torch to remove it. The new cross-member section must be cut, put in place and welded back together. This process is very time consuming and expensive.
There is a need for a cross-member system that is lightweight, able to handle the stress placed on it by the frame rails due to heavy loads and is easily serviced.